Plunger pump



June 20, 1961 w. WILKENLOH ETAL PLUNGER PUMP 2 Sheets-Sheet 2 Filed March 1 1957 W 7 r fw ww J7 Cnu fill y w/ i? United States Patent 2,989,001 PLUNGER PUMP Wilhelm Wilkenl'oh and Erich Jiiger, both of Duisburg- Wanheim, Germany, assignors to Rheinstahl Wanheim Gesellschaft mit beschrankter Haftung Filed Mar. 1, 1957, Ser. No. 643,421 Claims priority, applicationGermany Mar. 7, 1956 12 Claims. (Cl. 103-37) The present invention relates to a plunger pump for press cylinders, and to hydraulic arrangements adapted to be used as props or jacks. For example, a press cylinder combined with the plunger pump of the present invention may be used as a prop extending between the floor and roof of a mine. It is known to provide in the low pressure cylinder of a two-cylinder pump a check valve which cooperates with a resilient element having a predetermined force to control the pressure of the fiuid. When the fluid pressure in the press cylinder reaches a certain value, the fluid in the low pressure cylinder opens the check valve against the force of the resilient element, and is thereupon free to return into the suction chamber. The disadvantage of'such constructions resides in their poor eificiency resulting from the choking of fluid in the check valve, as a great deal of energy used in operating such types of pumps is wasted.

An important object of the present invention, therefore, is to provide an improved pump structure of high efficiency, which is adapted to transmit to the high pressure piston substantially the entire force of the pistonrod during its compression stroke.

Another object of the present invention is to provide a piston pump which includes two or more pistons of diiferent eifective areas on a common carrier.

A further object of the .invention is to provide a pump of the above character including control apparatus which automatically cuts out, that is, renders inefiective, one or more pistons as the pressure of the fluid medium increases.

A further object of the invention is to provide aplunger pump with two or more pistons on a common carrier combined with means for automatically inactivating one or more pistons in a predetermined sequence.

A still further object of the invention is to provide a pump including two or more pistons of widely difierent diameters, which is capable of substantially reducing the no-load time of the pressing operation.

Another object of the invention is to provide a plunger pump of the character above set forth which requires short compression and suction strokes of the carrier.

A yet further object of the invention is to provide a plunger pump including two or more pistons on a common carrier combined with suction and pressure responsive valves in such manner that the pressure responsive valves successively and automatically inactivate one or more pistons when the pressure in the fluid medium rises.

A still further object of the invention is to provide a piston pump of the above defined character which is capable of rapidly expanding devices consisting of two or more telescopically joined members.

An additional object of the invention is to provide a plunger pump of the above character combined with a prop or jack comprising a plurality of telescopically joined members, which includes control means for regulating the velocity of expulsion of one member when such movement requires continuously increasing forces.

A yet further object of the invention is to provide a pump of the above character combined with a pair of telescopically joined relatively expansible members, which includes means for simultaneously regulating the velocity of expulsion of the inner member in dependency on the pressure of the fluid medium as the resistance to expansion increases.

Patented June 20, 1961 A more specific object of the invention is to provide, in combination with a plunger pump including two or more pistons on a common carrier, a control element adapted to cooperate with the carrier in a manner to successively or selectively inactivate one or more pistons in response to increasing pressures in the press cylinder.

Another specific object of the invent-ion is to provide, in combination with the plunger pump of the above character, two or more valves and a pressure responsive element adapted to selectively and automatically open the valves as the pressure of hydraulic fluid in the high pressure cylinder rises.

With the above objects in view the present invention mainly consists of novel pump means including two or more pistons on a common carrier. An operating means is connected to the pump means for moving the same through operating cycles each of which includes a pressure stroke and a suction stroke, and means, forming part of the pump means, is provided for inactivating or reactivating one or more pistons of the pump means during the operating cycles in dependency on the pressure of the compressed fluid medium.

In the preferred embodiment of the invention, each of those pistons which may eventually be inactivated by the rising pressure of the hydraulic fluid includes a suction valve means, and the pump is provided with an automatically operating pressure responsive element for opening the suction valve means during one of the strokes of the carrier, in response to the pressure of the fluid medium. The pressure responsive element may include a shiftable member which assumes different positions, controlled by the momentary pressure of the fluid, and thereby actuates or itself forms part of the suction valve means associated with the cylinders of the individual pump pistons. Individual valve means may be actuated independently from oneanother and in a predetermined sequence.

More specifically, the invention provides a pump adapted to be installed in a hydraulic prop or jack consisting of a plurality of telescoped tubes of which one serves as a suction chamber for the fluid and another as a press cylinder. The fluid is moved by the pump from the suction chamber directly into the press cylinder to quickly and efliciently expand the device. In accordance with this specific construction of the apparatus of the present invention, the pump includes a rigid piston member performing the dual functions of a lowand a highpressure piston. The piston member is provided in the inner tube of the prop or jack and is guided in the pressing piston. It has a limited freedom of movement with respect to and in the axial direction of the carrier, and performs, with certain other elements of the pumps the additional functions of a suction valve. A passage for the fluid medium may be provided between the carrier and the piston member, and a sealing member operating as a non-return valve between the highand the lowpressure cylinders of the pump is adapted to supplement the function of, or to altogether replace the fluid passage. A second sealing member, functioning as a nonreturn valve, is provided between the high pressure chamber and the press cylinder to alone control the inflow of hydraulic fluid into the latter even though the pump includes two or more cylinders. A control device, associated with the piston carrier, includes means responsive to pressure of the fluid medium in the press cylinder to move an element of the control device into difierent positions of equilibrium and with respect to the piston carrier and the piston member. During the compression stroke of the carrier, and while the pressure of the fluid medium in the press cylinder is below a certain value, the piston element is indirectly entrained by the carrier, but when the fluid pressure exceeds such value the piston member is positively engaged and moved by the carrier.

At low pressure of hydraulic fluid and during a compres sion stroke of the carrier, the control device seals the passages between the suction chamber and the low pressure cylinder while the fluid is free to communicate between the low pressure and the high pressure cylinders. At higher operating pressures, the fluid is free to communicate between the suction chamber and the low pressure cylinder, but is prevented from escaping from the both as to its construction and its method of operation,

together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read with the accompanying drawing.

In the drawing,

FIG. 1 is a longitudinal central section through one embodiment of a hydraulic plunger pump constructed in accordance with the present invention, part of the structure being schematically illustrated, and parts of certain elements broken away so as to be conveniently illustrated.

FIG. 2 is a longitudinal central section through a prop combined with a modified hydraulic pump, parts of the elongated tubes being broken away for the convenience of illustration; and

FIG. 3 is a longitudinal central section through a portion of the prop, illustrating a further embodiment of the hydraulic pump.

The pump illustrated in FIG. 1 is immersed in a pressure fluid, such as oil, and includes a hollow cylindrical body 1 defining low-, medium-, and high-pressure cylinders 2, 3 and 4, respectively, and a collecting chamber 5. The piston rod 6 carries a low pressure piston 7, an annular medium pressure piston 8, and an annular high pressure piston 9. Into the upper end of pump body 1 is fitted a closing member or lid 10. In the embodiment illustrated in FIG. 1, the piston 8 is integral with the end of piston rod 6 and carries the low pressure piston 7 which is attached thereto by one or more screws 7'. Piston 8 forms the enclosures for an exhaust valve 11 communicating with cylinder 3, and for a second exhaust valve 12 which communicates with the low pressure cylinder 2. A transverse bore 13, which connects the enclosures of valves 11 and 12, and an axial bore 14 together with radial bores 15 in the piston rod 6 provide a passage for communication of pressure fluid between the cylinders 2, 3 and the collecting chamber 5. A sealing ring 16 is provided in the annular recess 1' between cylinders 3 and 4, and is retained therein by a washer 16a which fits into the recess 1 and is itself retained therein by a split ring 16b. A second sealing ring 17 provided in the bore 1a in the pump body 1 is movable with the piston rod 6 in downward direction, indicated by arrow A, toward the collecting chamber 5 against the expansive force of a coil spring 18 housed in the collecting chamber. A third sealing ring 20 is provided in the chamber 5 adjacent a sealing nut 19, and is fixed by a split ring 20' on which rests a washer 18' in abutment with the lower end of the coil spring 18. A conduit 21, leading to the press cylinder (not shown), is welded to the exterior of the pump body 1 and communicates with the collecting chamber 5 through a transverse bore 21. The housing 1 further carries the enclosures of a suction valve 22 for the high pressure cylinder 4, of a second suction valve 23 for the low pressure cylinder 2, and of a third suction valve 24 for the medium pressure cylinder 3, as well as the enclosure of a control element 25 whose interior is in communication with the collection chamber 5 through a radial bore 25'. Valves 23 and 24 include conical members 26, 26' with outwardly extending projections 33, 33, respectively. The control element 25 houses a plunger 27, a sealing ring 247', a coil spring 28 and a closure 25a. Plunger 27 is mounted on the rod 29 and bears with one end'face against the shoulder 29', and with its other end face against the sealing ring 27' which is prevented from sliding ofl the rod 29 by a snap ring 27". The rod 29 projects through a bore in the upper end wall of the housing of control element 25 and is guided in a bearing 32 which is welded to the pump body 1. Members 30, 30, adjustably attached to the rod 29 by means of screws 31, 31', are movable by the rod 29 into engagement with, and away from, the valve projections 33, 33" of the respective valves 23, 24 to open same for the purposes to be fully set forth hereinafter. Valves 1 1, 12, 22, 23 and 24 are of known construction, therefore, only those of their elements are identified by numerals to which specific reference is made in the course of the following description of the pump operation.

During the compression stroke of the pump, while the piston rod 6 travels in the direction of arrow A, partial vacuum is created in the low pressure cylinder 2 and the fluid is free to enter therein through the suction valve 23. The fluid which fills the cylinder 3 is compressed by the piston 8 and opens valve 11, passes through the bore 13, the enclosure of the closed valve 12 and bores 14, 15 into the collecting chamber 5 and thence through the bore 21 and conduit 21 into the press cylinder of, for example, a mine prop or the like. There is also simultaneous flow of fluid under pressure from the high pressure cylinder 4, through the passages 4' and around the sealing ring 17, the latter following the downward movement of the piston rod 6, into the collecting chamber 5 and thence into the press cylinder. Thus, the sealing ring 17, together with the coil spring 18 in the collecting chamber 5, actually operates as a nonreturn valve.

During the suction stroke of the piston rod 6, the cylinders 4 and 3, now under partial vacuum, are filled with fluid medium which surrounds the pump body 1 through the open suction valves 22 and 24, respectively. The fluid travels from the cylinder 2 through the open valve 12 and the bores 14, 15 into the conduit 21. Should the piston of the press cylinder (not shown) meet an obstruction in its outward movement from the latter, the fluid pressure in control element 25 rises and causes the rod 29 to assume a different position of equilibrium, i.e., the plunger 27 and rod 29 with members 30, 30 travel upwardly against the expansive force of the coil spring 28. The distance between members 30' and 33' is somewhat greater than the distance between the member 30 and projection 33. Thus, at a predetermined pressure of the fluid in control element 25, the member 30 first engages projection 33 and opens the valve 23. This renders the piston 7 ineffective as the pressure fluid is now free to escape from the low pressure cylinder 2 through the open valve 23.

If the piston of the press cylinder meets an increasingly greater resistance and the pressure in control element 25 rises accordingly, the rod 29 moves the member 30' into engagement with the projection 33' to open the valve 24 and to cut out the piston 8. Thus, only the piston 9 remains active and continues to supply pressure fluid into the collecting chamber 5.

The three successive stages of operation of the pump and of movement of fluid under pressure into the collection chamber 5 are as follows:

(a) At the compressing stroke of the piston rod 6, pressure fluid enters the pump body 1 through the suction valve 23, and during the suction stroke through valves 22 and 24.

(b) After reaching a predetermined pressure in the chamber 5, the fluid causes element 29 to open the suction valve 23 and the piston 7 becomes ineffective. The

pressure stroke .of the piston rod brings no more fluid into the housing. The suction stroke, however, continues to actuate valves 22 and 24 to supply fluid to the mediumand high-pressure cylinders.

(c) After a further rise in pressure of fluid in the chamber 5, the control element 25 causes suction valve 24 to open, whereupon fluid is supplied to the pump body 1 by the sole valve 22 during the suction stroke of the piston rod 6.

The pump illustrated in FIG. 2 is built into the suction chamber 35 of a cylindrical tube 36, which is the movable inner member of a mine prop or the like. The outer tube 137 of the prop has a bore 37 defining a press cylinder 53 between the base 39 and the piston 40, the latter carrying a sealing ring 59. In the upper end of the bore 37' is received a guide socket 38. Press piston 40 is fastened to the lower end of the inner tube 36 by means of pins or screws 40. The upper end of the tube 36 is closed by an end wall member 41 which is retained therein by one or more fasteners 41'. Press piston 40 houses the high pressure cylinder 43 and with its upper end forms the bottom end wall 40 of a low pressure cylinder 44. A tubular piston rod 45 is axially guided in the prop and carries an integral collar-like projection 46. The piston rod 45 is guided in the bore of the sleeve 47a integral with a member 47' whose shoulder 47b is the lower end Wall of a chamber 47, and in the annulus 42 separating the high pressure cylinder 43 from the press cylinder 59.

A piston member 48 has an enlarged portion 49 operating as a low pressure piston and defining the upper end wall of the low pressure cylinder 44, and an elongated annular extension 56 spaced from the periphery of the piston rod 45 and extending into the high pressure cylinder 43, which acts as a high pressure piston. The annular passage between the inner face of piston Sit and the periphery of piston rod 45 is indicated by the reference numeral 52. The piston member 48 is guided in the bore 36' provided in the inner tube 36, and its projecting high pressure piston 50 in the cap 51 which is received in the bore a provided in the piston 40. The lower end (in the drawing) of the piston 50 rests on an annular carrier 53 which is prevented from movement in downward direction along the piston rod by a snap ring 53'. Bores 58 provide a communication between the inwardly tapering recess 48 in the upper face of the piston member 48 and the low pressure cylinder 44. In the cap 51 is provided a sealing ring 54 which is movable in downward direction against the force of a coil spring 72 in the cylinder 43. Piston 46 has an annular portion 42 which forms the lower end wall of the high pressure cylinder 43 and also receives a sealing ring 56 which is movable in downward direction against the force of a coil spring 57 in the press cylinder 59.

The collar 46 on the piston rod 45 is received in a cylindrical enclosure of the control element 60 whose lower end wall is below the collar 46 and is provided with a sealing edge or lip 71. The upper end of control element 60 is closed by a nut 61 which is guided along the periphery of the piston rod 45. The element 60 has limited freedom of movement against the force of a coil spring 62 positioned between the nut 61 and a washer 62. That portion of the interior of control element 60' which is above the collar 46 is made tight against the influx of pressure fluid from the surrounding suction chamber 35 by a pair of sealing rings 60a, 6012, respectively, and is in communication with the interior of the hollow piston rod 45 through radial bores 63.

A tubular member 64' is welded to, and extends through, the wall of the tube 36 to receive a crank 65 carrying a non-circular projection 64 at its outer face, and an eccentrically located crank pin 65 atits inner face. The crank pin 65' extends into a recess provided in the block 66 which is welded or otherwise fastened to the exterior of piston rod 45.

As before stated, the upper end of the piston rod 45 extends through the bore in the sleeve 47a which is carried by the partition 47 The latter also carries the enclosure for a valve 68 whose lower end wall 68a is the second end wall of the chamber 47. The valve cone 68', which norm-ally rests in its seat in the end wall 68a under the action of a spring 67,, is at the lower end of the stem 68" that extends from the enclosure of valve 68 and has an externally threaded end portion adjustably receiving a nut 67.

The nut 67' may be engaged by the eccentric pin 69 of a crank 70 which is received in a short tube 69 extending through a bore in the tubular member 36. Crank 70 has an external non-circular projection 70' which may be engaged and rotated by a suitable tool (not shown) to unseat the valve member 68, as will be described in more detail hereinafter.

In operation, the crank 65 is first turned in such direction as to effect a downward, i.e., compressing stroke of the piston rod 45 which carries the sealing lip 71 of the control element into contact with the upper face of the piston member 48 in its recess 48. During continued downward stroke of the piston rod 45, the pressure fluid is forced from the low pressure cylinder 44 through the bores 58 and the passage 52 into the high pressure cylinder 43, as the shoulder 55 is not in contact with the upper face of the piston member 48. The doubleacting piston member 48, which moves with the control element 60, causes the high pressure piston 50 to enter the cylinder 43 and to urge hydraulic fluid through bores 42' in the portion 42 of the press piston 40 and around the sealing ring 56 into the press cylinder 59. Thus, the sealing ring 56, together with the coil spring 57 which is sea-ted on an inner flange of the collar 57, forms a nonreturn valve which controls the flow of fluid from the high pressure cylinder 43 into the press cylinder 59, whereby the inner tube 36 is moved upwardly and out of the outer tube 37.

On continued turning of the crank to effect the suction stroke of the piston rod 45, the double-acting piston member 48 remains stationary until the element 53 reaches the lower end of the high pressure piston 50. However, the control member 60 moves with the upwardly traveling piston rod 45 to open an annular passage between its sealing lip 71 and the upper face of member 48, whereby the pressure fluid in chamber 35 is free to flow through the bores 58 into the low pressure cylinder 44, and through the annular passage 52 into the high pressure cylinder 43 until the piston rod 45 reaches its uppermost position. This cycle of alternating compression and suction strokes is then repeated until the end wall 41 at the upper end of the inner tube 36 hits the roof of the mine, i.e., when the back pressure in the hydraulic fluid which is forced into the press cylinder 59 begins to rise. Such pressure is transmitted to the fluid in the control element 60 above the collar 46 between the sealing rings 60a and 60b, as the press cylinder 59 is in communication with the interior of the element 60 through the axial bore 45 and transverse bores 63 in the piston rod 45. The control element 60 is caused to assume a new position of equlibrium by moving along the piston rod 45 against the force of coil spring 62. It will be seen that the lower sealing ring 66a is slidable in the interior of the cylindrical enclosure of element 60 and, when the pressure in the fluid reaches a predetermined value, bears against the collar 46 on the piston rod 45 and causes upward movement of the control element to the extent determined by the distance between collar 46 and the lower end wall of the enclosure of the element 60. The uppensealing ring 60b is locked in position against the nut 61 by a snap ring 6012. The interior of the enclosure for element 60 is subdivided by a partition 600 into a lower and an upper chamber, the latter of which communicates with the interior of piston rod 45 through the bores 63. The upper and the lower chamber in the enclosure of the valve element 60 are in communication through the bores 600. It will now be seen that the pressure fluid in the upper chamber in the enclosure of element 60 and penetrating through the bores 60c in the partition 60c causes the element 60 to move against the spring 62 until the lower end wall of the enclosure which carries the annular sealing lip 71 abuts against the lower face of the collar 46. The extent of downward movement of control element 60 along the periphery of the piston rod 45 and under the influence of spring 62 is determined by a shoulder 4511 which abuts against the partition 600, which position of the enclosure for element 60 is shown in FIG. 2.

In the previously described uppermost position of the enclosure for element 60 with respect to the piston rod 45, that is, when the lower end wall thereof abuts against the collar 46, the sealing lip 71 is prevented from coming into contact with the piston member 48. During the compression stroke of the piston rod 45, the piston member 48 is entrained by the shoulder 55, and the bores 58 in the piston 49 remain open, whereby the fluid is free to flow from the cylinder 44 back into the suction chamber 35. The low pressure piston 49 is thus ineffective.

In the phase of transition toward inactivation of the piston 49, i.e., when the control element 60 is partially lifted against the expanding force of resilient element 62, the compressing stroke of the piston rod 45 brings the shoulder 55 thereon sufficiently close to the adjacent upper face of the piston member 48 to achieve a substantial choking of the passage 52 and to reduce the amount of hydraulic fluid flowing from the low pressure chamber 44 back into the suction chamber 35. During such transitory cycle, and on compression stroke of the 7 piston rod 45, the pressure fluid is free to overflow from cylinder 44 into the high pressure cylinder 43 over the sealing ring 54 with but small pressure losses.

It will be seen that, because the sealing ring 54 together with the coil spring 72 acts as a non-return valve, the pump will also operate without the annular passage 52 which can be omitted altogether in certain embodiments, even though the efliciency of the pump is then somewhat reduced, i.e.,, the expulsion of the inner tube 36 under identical operating conditions is somewhat slower. This is due to certain pressure losses at the sealing ring 54.

For collapsing of the prop, when the inner tube should be returned into the outer member 37, crank 70 is turned until the pin 69 unseats the valve member 68' to open a passage for the pressure fluid from the press cylinder 59, through the bore 45' in the piston rod 45, chamber 47, bore in partition 68a and openings in the upper end wall of the enclosure for the valve 68 into the suction chamber 35.

When the pressure of fluid in chamber 59, in the interior of the piston rod 45, and in the chamber 47 reaches a predetermined maximum permissible value, the valve 68 may open automatically as the spring 67 yields to an excessive pressure in the fluid to release the valve cone 68 and to permit the passage of fluid in the previously disclosed manner. This adds a certain degree of resiliency to the prop, as the device will yield under an excessive load without any supervision or manipulation of the element 70.

A slightly modified piston rod 80 with a modified control element 74 is illustrated in FIG. 3. The piston rod carries a sleeve 76 which is prevented from movement in the upward direction, as shown in the drawing, by a snap ring 85 or the like. A coil spring 75 is provided between the flange 92 of the sleeve 76 and the upper end wall 86 of the cylindrical housing for the element 74. The lower end of the housing of element 74 is open to receive an annular protuberance or collar 77 on the piston rod 80, and is somewhat reduced, as at 87, to

form an intermediate shoulder 84. An external sealing ring 78 is recessed into the reduced portion 87 which fits into the circular recess 88 in the piston member 79. A second external sealing ring 81 is provided in the piston rod 80 immediately below the collar 77. That portion of the piston rod 80 into which is recessed the ring 81 fits into the annular passage 82 between the periphery of piston rod 80 and the reduced annular extension which corresponds in its shape to, and performs the functions of, the high pressure piston 50 illustrated in FIG. 2. Bores 83 provide a communication passage for pressure fluid between the low pressure cylinder 44 and the suction-chamber 35 on opposing sides of the piston member 79 which carries a sealing ring 91 and generally corresponds to the member 48 shown in FIG. 2.

The interior of the enclosure for control element 74 is sealed by a pair of rings 93, 94. Sealing ring 93 moves with the element 74, but the other ring 94 is fastened to the piston rod 80. The latter has an axial bore 95 and a plurality of radial bores 96 in communication with the interior of the enclosure for the control element 74.

The operation of the modified piston rod 80, piston member 79 and element 74 is as follows:

During the compression stroke of the piston rod 80, the reduced portion 87 of the enclosure for the element 74 and the ring 78 seal the bore 88 in the piston member 79. In the embodiment of FIG. 2, the edge or lip 71 on the lower end face of the valve 60 performs an analogous function. When the shoulder 84 meets with the upper face of the piston member 79, the latter begins to move with the descending piston rod 80 and the high pressure piston 90, entering the cylinder 43 (see FIG. 2), expels the fluid through the bores 42 into the press cylinder 59. The pressure fluid can flow from the low pressure cylinder 44, through the bores 83, through the recess 88 which is closed by the lower face of the sleeve 77 and the reduced portion 87 of the enclosure 74, and through the passage 82 into the high pressure cylinder 43. As the pressure in the cylinder 59, bores 95, 96 and in the enclosure for the element 74 increases, the latter moves against the force of the spring 75 in the direction of, and into abutment with, the sleeve 76. In this position of the element 74, the sealing ring 78 is moved from the bore 88 and slides along the collar 77 whose lower face engages the piston member 79 and moves it together with the descending piston rod 60. The passage 82 is now sealed by the ring 81, but the fluid is free to communicate between the cylinder 44 and the chamber 35 through the bores 83 in the piston member 79. The low pressure piston is cut out.

It will be seen that the embodiment illustrated in FIG. 3 provides a better seal between the piston rod 80 and the piston member 79 than the arrangement of FIG. 2, but requires a longer stroke of the piston rod. Thus, the selection of the more suitable mechanism will depend on certain factors in accordance with specific requirements and circumstances under which the pump is put to use.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of hydraulic props or jacks differing from the types described above, as well as in other devices in which one or more members are desired to be moved under controlled speed and pressure conditions.

While the invention has been illustrated and described as embodied in pump arrangements for hydraulic props or jacks, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics 9- of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A hydraulic plunger pump, comprising, in combination, a tubular body having a closed end and an open end; a member in said open end having an axial bore; a supply of pressure fluid in said body; a relatively small first cylinder in said body attached to said member; a first piston in said body adapted to extend into said first cylinder; a second piston in said body connected with said first piston between said, first cylinder and said fluid; said second piston and said member between themselves defining a second cylinder; said second piston having openings for the flow of said fluid into said second cylinder; a first non-return valve means for the flow of said fluid from said first cylinder and through said member; a second non-return valve means for the flow of said fluid from said second cylinder into said first cylinder; a hollow piston rod axially extending through said bore in said member, through said first piston and said second piston, and through said first cylinder and said second cylinder; said rod having an open end in its: extremity extending through said bore in said member; said rod and said first piston between themselves defining an annular passage for the flow of said fluid into said first cylinder; operating means connected with said rod for moving same through cycles each of which includes a pressure stroke and a suction stroke and for moving said first piston and said second piston for 'at least a part of said strokes; shoulder means on said rod for at least partially closing said passage during said pressure strokes; and pressure responsive means adjacent said second piston, said pressure responsive means including a substantially cylindrical member axially traversed by and slidable on said rod, said cylindrical member defining an internal chamber in communication with the interior ofsaid rod, means on said rod for engaging and moving said cylindrical member for at least a part of each of said strokes, resilient means for urging said cylindrical member to ward said second piston for closing said openings during said pressure strokes, and means defining apertures for flo-w of said fluid between said openings and said passage integral with said cylindrical member, said cylindrical member being adapted to move on said rod in a direction away from said piston when the pressure of said fluid in said chamber increases.

2. A hydraulic plunger pump adapted to feed fluid into a pressure vessel, comprising in combination, an enclosure defining at least a low pressure cylinder and a high pressure cylinder; at least a low pressure pistonand a high pressure piston respectively located in said cylinders; a common carrier for said pistons; operating means connected to said carrier for moving the same along the axis thereof in opposite directions through a given distance and for moving said pistons carried by said carrier in opposite directions at least part of said distance through a pressure stroke and a suction stroke; fluid inlet means in communication with said low pressure cylinder;

valve means for said fluid inlet means; pressure-responsive means including control cylinder means and control piston means, one of said control means being movable relative to the other if the pressure in said prwsure vessel exceeds a predetermined limit, said movable means form ing one unit with said valve means for said fluid inlet means in such a manner that upon surpassing of said predetermined pressure in said pressure vessel said inlet valve means for said fluid inlet means is automatically kept open; and second fluid inlet means communicating with said high pressure cylinder.

3. A hydraulic plunger pump adapted to feed fluid into a pressure vessel, comprising, in combination, an enclo- Sure defining at least a low pressure cylinder and a high 10 pressure cylinder; at least a low pressure piston and a high pressure piston respectively located in said cylinders; a common carrier for said pistons; operating means connected to said carrier for moving the same along the axis thereof in opposite directions through a given distance and for moving said pistons carried by said carrier in opposite directions at least part of said distance through a pressure stroke and a suction stroke; fluid inlet means in said low pressure piston; valve means for said fluid inlet means; pressure-responsive means including control cylinder means and control piston means, one of said control means being movable relative to the other if the pressure in said pressure vessel exceeds a predetermined limit, said movable means forming one unit with said valve means for said fluid inlet means in such a manner that upon surpassing of said predetermined pressure in said pressure vessel said inlet valve means for said fluid inlet means is automatically kept open; and second fluid inlet means communicating with said high pressure cylinder.

4. A hydraulic plunger pump adapted to feed fluid into a pressure vessel, comprising in combination, an enclosure defining at least a low pressure cylinder and a high pressure cylinder; at least a low pressure piston and a high pressure piston respectively located in said cylinders; a common tubular carrier for said pistons extending with an. open end thereof into said pressure vessel; operating means connected to said carrier for moving the same along the axis thereof in opposite directions a given distance and for moving said pistons carried by said carrier for at least part of said distance through a pressure and a suction stroke; fluid inlet means in said low pressure piston; pressure-responsive means including control cylinder means arranged about said tubular carrier and control piston means in said control cylinder means and connected to said carrier for moving therewith; passage means providing communication between the interior of said tubular carrier and said control cylinder means, said control cylinder means being movable relative to said control piston means and said carrier between an operative position in which, during the stroke of said carrier in one direction said control cylinder means engages said low pressure piston for moving the same through its pressure stroke while closing at the same time said fluid inlet means in said low pressure piston so that fluid in said low pressure cylinder will be compressed during said pressure stroke, and a non-operative position in which said control cylinder remains spaced from said low pressure piston during movement of said carrier in said one direction so that said inlet means in said low pressure piston remains open, said control cylinder moving from said operative position into said non-operative position when the pressure in said pressure vessel transmitted through said tubular carrier and said passage means into said control cylinder means surpasses a predetermined pressure; and second fluid inlet means communicating with said high pressure cylinder.

5. A hydraulic plunger pump adapted to feed fluid into a pressure vessel, comprising in combination, an enclosure defining at least a low pressure cylinder and a high pressure cylinder; at least a low pressure piston and a high pressure piston respectively located in said cylinders; a common tubular carrier for said pistons extending with an open end thereof into said pressure vessel; operating means connected to said carrier for moving the same along the axis thereof in opposite directions a given distance and for moving said pistons carried by said carrier for at least part of said distance through a pressure and a suction stroke; fluid inlet means in said low pressure piston; pressure-responsive means including control cylinder means arranged about said tubular carrier and control piston means in said control cylinder means and connected to said carrier for moving therewith; passage means providing communication between the interior of said tubular carrier and said control cylinder means, said control cylinder means being movable relative to said control piston means and said carrier between an operative position in which, during the stroke of said carrier in one direction said control cylinder means engages said low pressure piston for moving the same through its pressure stroke while closing at the same time said fluid inlet means in said low pressure piston so that fluid in said low pressure cylinder will be compressed during said pressure stroke, and a non-operative position in which said control cylinder remains spaced from said low pressure piston during movement of said carrier in said one direction so that said inlet means in said low pressure piston remains open, said control cylinder moving from said operative position into said non-operative position when the pressure in said pressure vessel transmitted through said tubular carrier and said passage means into said control cylinder means surpasses a predetermined pressure; resilient means engaging said control cylinder means and tending to move the same against the pressure transmitted thereto from the pressure vessel into said operative position thereof; and second fluid inlet means communicating with said high pressure cylinder.

6. A hydraulic plunger pump adapted to feed fluid into a pressure vessel, comprising in combination, an enclosure defining at least a low pressure cylinder and a high pressure cylinder; at least a low pressure piston and a high pressure piston respectively located in said cylinders; a common tubular carrier for said pistons extending with an open end thereof into said pressure vessel; operating means connected to said carrier for moving the same along the axis thereof in opposite directions a given distance and for moving said pistons carried by said carrier for at least part of said distance through a pressure and a suction stroke; fluid inlet means in said low pressure piston; second fluid inlet means communicating with said high pressure cylinder; pressure-responsive means including control cylinder means arranged about said tubular carrier and control piston means in said control cylinder means and connected to said carrier for moving therewith; passage means providing communication between the interior of said tubular carrier and said control cylinder means, said control cylinder means being movable relative to said control piston means and said carrier between an operative position in which, during the stroke of said carrier in one direction said control cylinder means engages said low pressure piston for moving the same through its pressure stroke while closing at the same time said fluid inlet means in said low pressure piston so that fluid in said low pressure cylinder will be compressed during said pressure stroke, and a non-operative position in which said control cylinder remains spaced from said low pressure piston during movement of said carrier in said one direction so that said inlet means in said low pressure piston remains open, said control cylinder moving from said operative position into said non-operative position when the pressure in said pressure vessel transmitted through said tubular carrier and said passage means into said control cylinder means surpasses a predetermined pressure; resilient means engaging said control cylinder means and tending to move the same against the pressure transmitted thereto from the pressure vessel into said operative position thereof; and means on said tubular carrier for engaging said pistons to move the latter during the stroke of said carrier in said one direction while said control cylinder is in said non-operative position.

7. A hydraulic plunger pump adapted to feed fluid into a pressure vessel, comprising in combination, an enclosure defining at least a low pressure cylinder and a high pressure cylinder; at least a low pressure piston and a high pressure piston respectively located in said cylinder; a common tubular carrier for said pistons extending with an open end thereof into said pressure vessel; operating means connected to said carrier for moving the same along the axis thereof in opposite directions a given distance and for moving said pistons carried by said carrier for at least part of said distance through a pressure and a suction stroke; fluid inlet means in said low pressure piston; second fluid inlet means communicating with said high pressure cylinders; pressure-responsive means including control cylinder means arranged about said tubular carrier and control piston means in said control cylinder means and connected to said carrier for moving therewith; passage means providing communication between the interior of said tubular carrier and said control cylinder means, said control cylinder means being movable relative to said control piston means and said carrier between an operative position in which during the stroke of said carrier in one direction said control cylinder means engages said low pressure piston for moving the same through its pressure stroke while closing at the same time said fluid inlet means in said low pressure piston so that fluid in said low pressure cylinder will be compressed during said pressure stroke, and a non-operative position in which said control cylinder remains spaced from said low pressure piston during movement of said carrier in said one direction so that said inlet means in said low pressure piston remains open, said control cylinder moving from said operative position into said non-operative position when the pressure in said pressure vessel transmitted through said tubular carrier and said passage means into said control cylinder means surpasses a predetermined pressure; resilient means engaging said control cylinder means and tending to move the same against the pressure transmitted thereto from the pressure vessel into said operative position thereof; and means on said tubular carrier for engaging said pistons to move the latter during the stroke of said carrier in said one direction while said control cylinder is in said non-operative position and for closing said second fluid inlet means during said engagement.

8. A hydraulic plunger pump adapted to feed fluid lnto a pressure vessel, comprising in combination, an enclosure defining at least a low pressure cylinder and a high pressure cylinder; at least a low pressure piston and a high pressure piston respectively located in said cylinders; a common tubular carrier for said pistons extending with anopen end thereof into said pressure vessel; operating means connected to said carrier for moving the same along the axis thereof in opposite directions a given distance and for moving said pistons carried by said carrier for at least part of said distance through a pressure and a suction stroke; fluid inlet means in said low pressure piston; second fluid inlet means communicating with said high pressure cylinder; pressure-responsive means including control cylinder means arranged about said tubular carrier and control piston means in said control cylinder means and connected to said carrier for moving therewith; passage means providing communica tion between the interior of said tubular carrier and said control cylinder means, said control cylinder means being movable relative to said control piston means and said carrier between an operative position in which, during the stroke of said carrier in one direction said control cylinder means engages said low pressure piston for moving the same through its pressure stroke while closing at the same time said fluid inlet means in said low pressure piston so that fluid in said low pressure cylinder will be compressed during said pressure stroke, and a nonoperative position in which said control cylinder remains spaced from said low pressure piston during movement of said carrier in said one direction so that said inlet means in said low pressure piston remains open, said control cylinder moving from said operative position into said non-operative position when the pressure in said pressure vessel transmitted through said tubular carrier and said passage means into said control cylinder means surpasses a predetermined pressure; resilient means engaging said control cylinder means 'and tending to move the same against the pressure transmitted thereto from the pressure vesselinto said operative position thereof; means on said tubular carrier for engaging said pistons to move the latter during the stroke of said carrier in said one direction while said control cylinder is in said non operative position and for closing said second fluid inlet means during said engagement; and passage means establishing communication between said low pressure cylinder and said inlet means of said high pressure cylinder during at least part of the movement of said low pressure piston along the compression stroke thereof.

9. A hydraulic plunger pump adapted to feed fluid into a pressure vessel, comprising in combination, an enclosure defining at least a low pressure cylinder and a high pressure cylinder; at least a low pressure piston and a high pressure piston respectively located in said cylinders; a common tubular carrier for said pistons extending with an open end thereof into said pressure vessel; operating means connected to said carrier for moving the same along the axis thereof in opposite directions a given distance and for moving said pistons carried by said carrier for at least part of said distance through a pressure and a suction stroke; fluid inlet means in said low pressure piston; second fluid inlet means communicating with said high pressure cylinder arranged between the outer surface of said tubular carrier and the inner surface of said pistons arranged about said carrier; pressure-responsive means including control cylinder means arranged about said tubular carrier and control piston means in said control cylinder means and connected to said carrier for moving therewith; passage means providing communication between the interior of said tubular carrier and said control cylinder means, said control cylinder means being movable relative to said control piston means and said carrier between an operative position in which, during the stroke of said carrier in one direction said con trol cylinder means engages said low pressure piston for moving the same through its pressure stroke while closing at the same time said fluid inlet means in said low pressure piston so that fluid in said low pressure cylinder will be compressed during said pressure stroke, and a non-operative position in which said control cylinder remains spaced from said low pressure piston during movement of said carrier in said one direction so that said inlet means in said low pressure piston remains open, said control cylinder moving from said operative position into said non-operative position when the pressure in said pressure vessel transmitted through said tubular carrier and said passage means into said control cylinder means surpasses a predetermined pressure; resilient means engaging said control cylinder means and tending to move the same against the pressure transmitted thereto firom the pressure vessel into said operative position thereof; and means on said tubular carrier for engaging said pistons to move the latter durmg the stroke of said carrier in said one direction while said control cylinder is in said non-op=erative position and for closing said second fluid inlet means during said engagement.

10. A hydraulic plunger pump adapted to feed fluid into a pressure vessel, comprising in combination, an enclosure defining at least a low pressure cylinder and a high pressure cylinder; at least a low pressure piston and a high pressure piston respectively located in said cylinders; a common tubular carrier for said pistons extending with an open end thereof into said pressure vessel; operating means connected to said carrier for moving the same along the axis thereof in opposite directions a given (118- tance and for moving said piston carried by said carrier for at least part of said distance through a pressure and a suction stroke; fluid inlet means in said low pressure piston; pressure-responsive means including control cylinder means arranged about said tubular carrier and control piston means in said control cylinder means and connected to said carrier for moving therewith; passage means providing communication between the interior of said tubular carrier and said control cylinder means, said control cylinder means being movable relative to said control piston means and said carrier between an operative position in which, during the stroke of said carrier in one direction said control cylinder means engages said low pressure piston for moving the same through its pressure stroke while closing at the same time said fluid inlet means in said low pressure piston so that fluid in said low pressure cylinder will be compressed during said pressure stroke, and a non-operative position in which said control cylinder remains spaced from said low pressure piston during movement of said carrier in said one direction so that said inlet means in said low pressure piston remains open, said control cylinder moving from said operative position into said non-operative position when the pressure in said pressure vessel transmitted through said tubular carrier and said passage means into said control cylinder means surpasses a predetermined pressure; and movable sealing means located between said low pressure cylinder and said high pressure cylinder arranged about said tubular carrier and acting as a non-return valve between said low pressure cylinder and high pressure cylinder.

11. A hydraulic plunger pump adapted to feed fluid into a pressure vessel, comprising in combination, an enclosure defining at least a low pressure cylinder and a high pressure cylinder; at least a low pressure piston and a high pressure piston respectively located in said cylinders; a common tubular carrier for said pistons extending with an open end thereof into said pressure vessel; operating means connected to said carrier for moving the same along the axis thereof in opposite directions a given distance and for moving said pistons carried by said carrier for at least part of said distance through a pressure and a suction stroke; fluid inlet means in said low pressure piston; pressure-responsive means including control cylindcr means arranged about said tubular carrier and control piston means in said control cylinder means and connected to said carrier for moving therewith; passage means providing communication between the interior of said tubular carrier and said control cylinder means, said control cylinder means being movable relative to said control piston means and said carrier between an operative position in which, during the stroke of said carrier in one direction said control cylinder means engages said low pressure piston for moving the same through its pressure stroke while closing at the same time said fluid inlet means in said low pressure piston so that fluid in said low pressure cylinder will be compressed during said pressure stroke, and a non-operative position in which said control cylinder remains spaced from said low pressure piston during movement of said carrier in said one direction so that said inlet means in said low pressure piston remains open, said control cylinder moving from said operative position into said non-operative position when the pressure in said pressure vessel transmitted through said tubular carrier and said passage means into said control cylinder means surpasses a predetermined pressure; movable sealing means located between said low pressure cylinder and said high pressure cylinder arranged about said tubular carrier and acting as a non-return valve between said low pressure cylinder and high pressure cylinder; and second movable sealing means located between said high pressure cylinder and said pressure vessel arranged about said tubular carrier and acting as a nonreturn valve between said high pressure cylinder and said pressure vessel.

12. A hydraulic plunger pump adapted to feed fluid into a pressure vessel, comprising in combination, an enclosure defining at least a low pressure cylinder and a high pressure cylinder; at least a low pressure piston and a high pressure piston respectively located in said cylinders; a common tubular carrier for said pistons extending with an open end thereof into said pressure vessel; operating means connected to said carrier for moving the same along the axis thereof in opposite directions a given distance and for moving said pistons carried by said carrier for at least part of said distance through a pressure and a 15 suction stroke; fluid inlet means in' said low pressure piston; second fluid inlet means communicating with said high pressure cylinder; a pressure-responsive means including control cylinder means arranged about said tubular carrier and control piston means in said control cylinder means and connected to said carrier for moving therewith; passage means providing communication between the interior of said tubular carrier and said control cylinder means, said control cylinder means being movable relative to said control piston means and said carrier between an operative position in which, during the stroke of said carrier in one direction said control cylinder means engages said low pressure piston for moving the same through its pressure stroke while closing at the same time said fluid inlet means in said low pressure piston so that fluid in said low pressure cylinder will be compressed during said pressure stroke, and a non-operative position in which said control cylinder remains spaced from said low pressure piston during movement of said carrier in said one direction so that said inlet means in said low pressure piston remains open, said control cylinder moving from said operative position into said non-operative position when the pressure in said pressure vessel transmitted through said tubular carrier and said passage means into said control cylinder means surpasses a predetermined pressure; resilient means engaging said control cylinder means and tending to move the same against the pressure transmitted thereto from the pressure vessel into said operative position thereof; means on said tubular carrier for engaging said pistons to move the latter during the stroke of said carrier in said one direction While said control cylinder is in said non-operative position and for closing said second fluid inlet means during said engagement; and means on said tubular carrier for moving said low pressure piston and said high pressure piston during the movement of said carrier in the other direction through part of said carrier stroke and only after said inlet means for said low pressure cylinder and said high pressure cylinder have been opened.

References Cited in the file of this patent UNITED STATES PATENTS 833,457 Hammond Oct. 16, 1906 895,666 Nelson Aug. 11, 1908 904,557 Nelson Nov. 24,1908 909,647 Nelson Jan. 12, 1909 1,080,062 Hess Dec. 2, 1913 1,521,461 Madden Dec. 30, 1924 2,091,876 Oldham Aug. 31, 1937 2,435,326 Schwerin Feb. 3, 1948 2,447,650 Haumerson Aug. 24, 1948 2,659,307 Framhein Nov. 17, 1953 2,713,773 Sutton July 26, 1955 2,820,415 Born Jan. 21, 1958 FOREIGN PATENTS 354,726 Italy Dec. 6, 1937 

